miR-140-3p/usp36 axis mediates ubiquitination to regulate PKM2 and suppressed the malignant biological behavior of breast cancer through Warburg effect

Breast cancer is a phenomenon in which breast epithelial cells proliferate out of control under the action of various carcinogenic factors. However, the role of USP36 in breast cancer is unknown. We analyzed the expression of USP36 in breast cancer and its association with poor prognosis in breast cancer patients. The effect of USP36 on malignant biological behavior of breast cancer was verified by cell functional experiments. The upstream regulatory mechanism of USP36 was analyzed by Western blot and quantitative RT-qPCR. The influence of USP36 on the Warburg effect of breast cancer was analyzed by detecting the metabolism of cellular energy substances. We found that USP36 is highly expressed in breast tumor tissues and breast cancer cell lines. High expression of USP36 predicts poor prognosis in patients with breast cancer. Effectively reducing the expression of USP36 can significantly inhibit the proliferation, invasion and migration of breast cancer cells, and promote the apoptosis of breast cancer cells. Meanwhile, inhibiting the expression of USP36 can significantly inhibit the production of ATP, lactate, pyruvate and glucose uptake in breast cancer cells. miR-140-3p is an upstream regulator of USP36, which can partially reverse the regulatory effect of USP36 on breast cancer cells. Importantly, USP36 regulates the expression of PKM2 through ubiquitination, which plays a role in regulating the Warburg effect. We confirmed that miR-140-3p regulates the expression of USP36, which mediates ubiquitination and regulates the expression of PKM2, and regulates the malignant biological behavior of breast cancer through the energy metabolism process.

乳腺癌是指乳腺上皮细胞在多种致癌因子作用下发生失控性增殖的病理现象。然而，泛素特异性蛋白酶36（USP36）在乳腺癌中的作用尚未明确。本研究分析了USP36在乳腺癌组织中的表达情况，及其与乳腺癌患者不良预后的相关性；通过细胞功能实验验证了USP36对乳腺癌细胞恶性生物学行为的影响；采用蛋白质印迹（Western blot）与逆转录实时定量聚合酶链反应（RT-qPCR）分析了USP36的上游调控机制；通过检测细胞能量物质代谢水平，分析了USP36对乳腺癌细胞瓦伯格效应（Warburg effect）的影响。研究发现，USP36在乳腺肿瘤组织及乳腺癌细胞系中均呈高表达状态；USP36高表达可提示乳腺癌患者预后不良。有效下调USP36的表达水平，可显著抑制乳腺癌细胞的增殖、侵袭与迁移能力，并促进其凋亡。同时，抑制USP36的表达可显著降低乳腺癌细胞内三磷酸腺苷（ATP）、乳酸（lactate）、丙酮酸（pyruvate）的生成量，并减少葡萄糖摄取。微小RNA-140-3p（miR-140-3p）是USP36的上游调控因子，可部分逆转USP36对乳腺癌细胞的调控作用。值得注意的是，USP36可通过泛素化（ubiquitination）调控丙酮酸激酶M2（PKM2）的表达，而该过程在瓦伯格效应的调控中发挥关键作用。本研究证实，miR-140-3p通过调控USP36的表达，介导泛素化过程并调节PKM2的表达，最终通过能量代谢途径调控乳腺癌细胞的恶性生物学行为。